JPS63225563A - Coating material for optical glass fiber - Google Patents

Abstract

PURPOSE:To obtain the title industrially useful coating material having a high cure rate, excellent toughness, and high reliability from a specified compd., the oligomer of urethane (meth)acrylate, a photopolymerization initiator, and the ester of a diol and (meth)acrylic acid. CONSTITUTION:(A) The urethane (meth)acrylate olygomer having 500-10,000 number average mol.wt., (B) a compd. acting as the reactive diluent for the A component, having >=1 polymerizable C-C double bond in one molecule, and being a low-viscosity liq. at ordinary temp., and (D) the ester of 2-ethyl-1,3- hexanediol and (meth)acrylic acid are mixed. In this case, 50-90wt.% (A+B) component and 50-10wt.% D component are mixed, and the content of the A component in the (A+B+D) component is adjusted to 30-70wt.%. The photopolymerization initiator (C) is added to the obtained mixture to the extent of 0.1-10wt.% of the (A+B+D) component, and a composition having 1,000-10,000cps/25 deg.C viscosity is obtained. The composition is coated on the surface of an optical fiber, irradiated by UV rays at 50-300mJ/cm<2>, and cured to form the coating material for optical glass fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to materials for coating optical glass fibers for light transmission.

[Conventional technology]

The resin coating of optical glass fibers (hereinafter referred to as optical fibers) is usually coated with a secondary coating for an inner layer with good flexibility such as silicone rubber, and then a secondary coating for a strong outer layer with a high tensile modulus that stretches on top of that. Covered. Conventionally, UV-curable materials with fast curing speed have been mainly used as secondary coating materials for the outer layer, and typical examples include:
Main material is urethane (meth)acrylate oligomer,
It is known that a reactive diluent and a photopolymerization initiator are added to this.

[Problem that the invention seeks to solve]

However, the conventional UV-curable materials based on urethane (meth)acrylate oligomers and sesame, which are known as secondary coating materials, are not fully satisfactory in terms of toughness of the cured product. First, there were problems in that it had a particularly low modulus of elasticity, had no resistance to lateral pressure, and had a rather slow curing speed.

Therefore, the present invention solves the above-mentioned conventional problems and improves the productivity of optical fibers by increasing the curing speed.
In addition, the cured product has high elongation and high elastic modulus, and is an industrially useful coating material for optical fibers that greatly contributes to improving the reliability of optical fibers by preventing increases in transmission loss caused by insufficient toughness. is intended to provide.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors found that when using a conventional ultraviolet curable material mainly composed of urethane (meth)acrylate oligomer, a specific compound is further used as a curable component. The inventors discovered that it is possible to obtain a coating material for optical fibers that cures quickly, has a large elongation, and can provide a tough cured product with a high modulus of elasticity, leading to the completion of this invention.

That is, the present invention is directed to a) a urethane (meth)acrylate oligomer, and b) a urethane (meth)acrylate oligomer containing one or more polymerizable carbon-carbon double bonds in one molecule, which has a small (and has) the action as a reactive diluent of the above-mentioned component a. In addition to the above components a, b, and c, d) 2-ethyl-1,3-hexanediol and (C) a photopolymerization initiator. The present invention relates to an optical fiber coating material containing an ester with meth)acrylic acid.

In addition, in this specification, the (meth)acryloyl group refers to an acryloyl group and/or a methacryloyl group,
(Meth)acrylate means acrylate and/or methacrylate, and (meth)acrylic acid means acrylic acid and/or methacrylic acid, respectively.

In addition, the number average molecular weight (hereinafter referred to as MW) described in this specification refers to a value measured by gel permeation chromatography (GPC) using polystyrene as a standard, and viscosity refers to a value measured by gel permeation chromatography (GPC) using polystyrene as a standard. Each term shall mean a value measured by a viscometer.

[Structure and operation of the invention]

The urethane (meth)acrylate oligomer as component a used in this invention has a urethane bond in its molecular skeleton, and has two or more (meth)acryloyl groups, usually up to six, in the molecule, and generally has a MW of 500. ~10
,000, which broadly includes conventionally known urethane (meth)acrylates. Specific examples include urethane (meth)acrylate oligomers such as polyether, polyester, polycaprolactone, and polycarbonate.

These urethane (meth)acrylate oligomers are
Compared to other (meth)acrylate oligomers used in ultraviolet curable materials, the cured product has a large elongation and a relatively good tensile modulus. However, by simply combining this oligomer with a reactive diluent as component b, it is difficult to increase both elongation and tensile modulus and provide excellent toughness, and there are also difficulties in terms of curability. be. Therefore, in the present invention, a specific curable component as the d component, which will be described later, is used in combination to improve the above characteristics.

The above urethane (meth)acrylate oligomer can be produced by using, for example, a polyether polyol, polyester polyol, polycaprolactone polyol, polycarbonate polyol, etc. as a polyol component, and reacting these polyols with a diisocyanate compound and further with a hydroxyalkyl (meth)acrylate. can be obtained by

Examples of the above diisocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, bis(isocyanate methyl)cyclohexane, dicyclohexylmethane diisocyanate, and 1,6-hexane diisocyanate, each having a molecular weight of 100 to 1,000.
Various compounds of about 0 are used. In addition, the above-mentioned hydroxyalkyl (meth)acrylate includes 2-
Those having a hydroxyalkyl group having about 2 to 5 carbon atoms, such as hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate, are used.

Since the urethane (meth)acrylate oligomer of component a is usually solid or highly viscous at room temperature, the compound used as component b, which is liquid at room temperature, used in this invention is made by adjusting the viscosity as a coating material. It is used to improve workability when coating fibers, but it also acts as an effective component to adjust the flexibility and hardness of the cured film.

As the b component, a compound having one or more polymerizable carbon-carbon double bonds, preferably 1 to 6 polymerizable carbon-carbon double bonds in the molecule and which is a low viscosity liquid at room temperature is used. is in the range of about 2 to 2,000 centivoices/25°C.

This compound is not limited to one type, but two or more types can be used in combination,
When used together, the properties of the mixture should be as described above. Therefore, one of them may be solid or have high viscosity at room temperature.

The molecular weight of component b is usually 90 to 2,000.
That's about it.

Specific examples of the above-mentioned components include those having a (meth)acryloyl group as a polymerizable carbon-carbon double bond, such as 2
- Ethylhexyl (meth)acrylate, tetrahydrofurfuryl alcohol caprolactone adduct (meth)
Acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, bisphenol diethylene glycol di(meth)acrylate, hydrogenated bisphenol triethylene glycol di(meth)acrylate, alicyclic di(meth)acrylate, trimethylolpropane Examples include mono- and poly(meth)acrylates such as tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and epoxy(meth)acrylate synthesized from bisphenol diglycidyl ether.

In addition, the above-mentioned components include allyl esters such as diallyl adipate, diallyl phthalate, triallyl trimellitate, and triallyl isocyanurate, styrene, vinyl acetate, N-vinylpyrrolidone, N-N-dimethyl (meth)acrylamide, N- Vinyl compounds such as N-dimethylaminopropyl (meth)acrylamide and N-N-dimethylaminoethyl (meth)acrylate can also be used.

The ester as the d component used in this invention is:
2-Ethyl=1,3-hexanediol and (meth)acrylic acid are mixed with an acidic compound such as hydrochloric acid, sulfuric acid, or p-)luenesulfonic acid in an amount of 0.1 to 10% by weight, preferably 0.1 to 10% by weight, usually as a catalyst. Contains two (meth)acryloyl groups in the molecule, obtained by esterification reaction at 80 to 120°C for 5 to 20 hours using 5 to 5% by weight in the presence of a polymerization inhibitor such as hydroquinone. It is a compound that

Such an ester containing a (meth)acryloyl group in the molecule as component d, when used in combination with components a and b, greatly contributes to improving the elongation and tensile modulus of the cured product, resulting in strong toughness. It also contributes to improving curability and significantly speeds up the curing rate by ultraviolet irradiation.

In this invention, the above-mentioned components a, b, and d are used as curable components, and the ratio of each component is 50 to 90%, preferably 60 to 80% per ton of the total of components a and b. d component is 50 to 10% by weight relative to the weight%
, preferably 40 to 20% by weight. If the amount of the d component is too small, the above-mentioned effects cannot be expected, and if it is too large, the elongation may gradually decrease. Note that the mutual ratio of components a and b can be set as appropriate from the viewpoint of cured product properties and coating workability depending on the type of each component. In general, it is preferable that the proportion of C component be 30 to 70% by weight in the total of components a, b, and d.

As the photopolymerization initiator used as component C in this invention, various kinds of initiators generally used as initiators and sensitizers for ultraviolet curable coatings can be used. For example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, 2-methylbenzoin, benzophenone, Michler's ketone, benzyl, penzyl dimethyl ketal, benzyl diethyl ketal, anthraquinone, methylanthraquinone, 2,2-jethoxyacetophenone. , 2-methylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, anthracene, l,1-dichloroacetophenone, methylorthobenzoylbenzoate, etc., and those used in combination with small amounts of sensitizing aids such as amines. can be mentioned.

The amounts of these photopolymerization initiators used include a, b,
Usually 0.1-1 per 1t100 parts by weight of the d component
The amount is approximately 0 parts by weight, preferably 1 to 5 parts by weight. If this amount is too small, the curability cannot be satisfied, and even if it is used in excess of a predetermined amount, no further improvement in the curing rate can be expected.

The optical fiber coating material of the present invention includes the above-mentioned a.

It contains component C in the above proportion along with components b and d, which may further contain acrylic resin, polyamide resin, polyester resin, polyether resin, polyurethane resin, polyamideimide resin/silicone resin, Various modifying resins such as phenol resins, and various additives such as organic silicon compounds and surfactants may be added, and the overall viscosity is usually 1°000 to 10.0° from the viewpoint of coating workability. 000 centiboise (c p
s) It is desirable that the temperature be adjusted within the range of (25°C).

The optical fiber coating material of the present invention having the above-mentioned structure is usually coated on the surface of the optical fiber with an inner layer coating that is softer than this material, and then coated thereon as an outer layer. The coating thickness at this time is preferably such that the thickness after curing is usually about 50 to 300 μm.
After this coating, it may be cured by irradiating light such as ultraviolet rays, and the irradiation amount may generally be about 50 to 300 mJ/aJ.
It has the characteristic that it can be cured much faster than conventional UV-curable materials.

Furthermore, by forming a tough coating such as a thermoplastic resin coating such as polyethylene or nylon as the outermost layer on the coating layer thus formed,
An optical fiber coating with even better fiber strength can be obtained.

〔Effect of the invention〕

As described above, in this invention, urethane (meth)
By including the specific compound as the d component in the optical fiber coating material that uses acrylate oligomer as the main component, the curing speed is fast and contributes to improving the productivity of optical fibers, and the cured product It has high elongation and tensile modulus, and has excellent toughness and flexibility, and has little increase in transmission loss due to lack of toughness. Therefore, it is extremely useful industrially as it greatly contributes to improving the long-term reliability of optical fibers. A coating material for optical fiber can be provided.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail. In addition, in the following, parts shall mean parts by weight.

Example 1 1 mole of 2-ethyl-1,3-hexanediol and 2 moles of acrylic acid were mixed in the presence of 5 parts of p-toluenesulfonic acid, 0.01 part of hydroquinone, and an amount of benzene capable of removing produced water at 90% After reacting at ~110°C for 17 hours,
After washing with water and removing benzene under reduced pressure, an ester containing two acryloyl groups in the molecule (hereinafter referred to as ester A) was obtained.

Next, polytetramethylene glycol (MWl, 00
0), tolylene diisocyanate, and 2-hydroxyethyl acrylate, 20 parts of the above ester A, 20 parts of bisphenol diethylene glycol diacrylate, 10 parts of vinylpyrrolidone, 3 parts of benzophenone, and 1 part of diethylaminoethanol were added. Mix and dissolve, viscosity 4.8
A coating material for optical fiber with a temperature of 00Cps (25°C) was obtained.

Comparative Example 1 Except that Ester A was not used and the amount of bisphenol diethylene glycol diacrylate used was 40 parts,
In the same manner as in Example 1, the viscosity was 3.500 cps (25
℃) coating material for optical fiber was obtained.

Example 2 Urethane acrylate oligomer 4 synthesized from polycaprolactone diol (MW 2,000), tolylene diisocyanate, and 2-hydroxyethyl acrylate
0 parts, 30 parts of ester A obtained in Example 1, 10 parts of bisphenol diethylene glycol diacrylate, 10 parts of vinylpyrrolidone, 3 parts of benzophenone, and 1 part of diethylaminoethanol were mixed and dissolved to give a viscosity of 6.300 cp.
A coating material for optical fiber was obtained.

Comparative Example 2 Except that Ester A was not used and the amount of bisphenol diethylene glycol diacrylate was 40 parts,
In the same manner as in Example 2, the viscosity was 5,000 cps.
(25° C.) An optical fiber coating material was obtained.

Example 3 Polyester polyol (MWI, 000) synthesized from ethylene glycol and adipic acid, 40 parts of urethane acrylate oligomer synthesized from tolylene diisocyanate and 2-hydroxyethyl acrylate, 40 parts of ester A obtained in Example 1, bisphenol 10 parts of diethylene glycol diacrylate, 10 parts of vinylpyrrolidone, 3 parts of benzophenone, and 1 part of diethylaminoethanol were mixed and dissolved to give a viscosity of 3,300 cps (25°C).
) coating material for optical fiber was obtained.

Comparative Example 3 Except that Ester A was not used and the amount of bisphenol diethylene glycol diacrylate used was 50 parts,
In the same manner as in Example 3, the viscosity was 2,300 cps (2
A coating material for optical fiber was obtained.

Test Example 1 After applying each coating material to a thickness of 0.2 mm on a glass plate,
It was cured using a high-pressure mercury lamp (80 W/cm), and the amount of ultraviolet irradiation (mJ/d) required for complete curing and the tensile modulus, elongation, and flexibility of the cured film were measured. The results were as shown in the table below.

The tensile modulus and elongation are measured according to JISK7113.
This was done in accordance with the. In addition, when bending the cured film peeled from the glass plate at 180 degrees, the flexibility was evaluated as O for those that did not break, Δ for those that were slightly damaged, and × for those that were significantly damaged.

<Test Example 2> Polyoxytetramethylene glycol (MW 2.0
00), tolylene diisocyanate, and 2-hydroxyethyl acrylate, 50 parts of urethane acrylate oligomer, 45 parts of acrylate of caprolactone adduct of tetrahydrofurfuryl alcohol, 5 parts of vinylpyrrolidone, 3 parts of benzophenone, and 1 part of diethylaminoethanol. The diameter after coating is 2
After coating to a thickness of 50 μm and curing at a linear speed of 100 m/min using a 160 W/as high-pressure mercury lamp, Examples 1 to 3 and Comparative Examples 1 to 3 were further applied for the outer layer.
The diameter after coating each optical fiber coating material is 4
00 μm, and cured at the same speed using the same high-pressure mercury lamp as above.

The optical fiber coated body thus obtained was prepared in Example 1.
The bobbin winding properties using the optical fiber coating materials No. 3 to 3 were very good and no increase in transmission loss was observed, but Comparative Examples 1 to 3 were significantly inferior to the above characteristics, with a loss of 1 dB/ It was observed that the transmission loss increased more than that of Jam.

Note that the bobbin winding characteristics are obtained by examining the increase in transmission loss when bobbin winding (tension 80 g) is performed on a drum having a diameter of 30 cm.

From the above test results, the coating material for optical fibers according to the present invention has a very slow curing speed and can provide a cured film with excellent toughness that contributes to improving the reliability of optical fibers. That is clear.

Claims (1)

[Claims] (1) a) Urethane (meth)acrylate oligomer,
b) a compound that is liquid at room temperature and has a low viscosity and contains one or more polymerizable carbon-carbon double bonds in one molecule, which has at least the effect of acting as a reactive diluent for component a; and c) a photopolymerization initiator. Coating materials for optical glass fibers, including
In addition to the above components a, b, and c, d) 2-ethyl-1,3
- A coating material for optical glass fiber characterized by containing an ester of hexanediol and (meth)acrylic acid.